SCIENCE QST Q4

• ·        Crust -the outermost layer of the earth

  -composed of continents and ocean basins

  Ocean Crust- composed of basalt

  Continental Crust- composed of granite rock
• Mantle-about 2900 km thick

  -it is divided into upper and lower mantles

  -composed of ferromagnesium silicates

  -the presence of plastic zone where lava originates
• Core

  - about 3500 km thick

  -it is divided into outer and inner core

  -composed of iron and nickel

  ­- hottest layer with a temp of 6,000 C to 10,000 C

  Outer core- liquid; 2,300 km thick

  Inner core- solid; 1,200 km thick
• ·        Continental Drift Theory- in 1912, Alfred Wegener, a German geophysicist. Supercontinent is refered as “Pangea” (meaning all land). States that forces on Earth’s crust caused it to break into separate crustal plates and it looks like a jigsaw puzzle
•   Plate Tectonic Theory- lithosphere is made up of several individual plates of different sized. It states that plates that carry continental and oceanic crusts are in constant motion
• Fold- when a rock is subjected to compressive stress, it begins to buckle and fold
• Folded Mountains- folding occurs when great pressure and high temperature push the horizontal layer of rocks. As a result, the anticline forms mountains and hills, the syncline forms valleys
• Crest or Anticline- elevated portion of the fold
• Syncline or Through- lower portion of the fold
• Faults- are fractures on rocks along which movement has occurred. It is the slippage of rock layers along the crack. Happens if one part moves relative to the other part, the fracture is called a fault
• Block Mountains- when faulting occurs over a wide area on Earth’s surface
• Earthquake- shaking of the ground. It happens when the crustal plate moves
• Seismograph- an instrument that measures the motion of the ground during earthquakes
• Seismograph- an instrument that can detect earthquakes.
• Seismologists- experts on earthquakes
• Seismogram- tracing earthquake motion
• Types of Earthquakes

  ·        Volcanic Earthquake- shaking off the ground. It happens in a strong volcanic eruption

  ·        Tectonic Earthquake- caused by movement of Earth’s crust or crustal plate or faulting

  NOTE: Tectonic Earthquake may occur above the ground or beneath the ocean
• Richter Scale- an instrument we use in measuring the earthquake’s magnitude. It was made by Charles F. Richter, he is an American seismologist.
• Magnitude- refers to the amount of energy released by an earthquake, from its focus. It uses numbers with decimals
• Intensity- refers to the effect of an earthquake, especially the damage. Uses roman numerals
• Mercalli Scale or Rossi-Forel Scale- an instrument used in measuring the intensity of an earthquake
• Focus- break in the ground caused by the pressure of the moving rocks. This is where the earthquake originates
• Epicenter- ground above the focus. Starting point of Earth’s surface of an earthquake
• Philippine Institute of Volcanology and Seismology (PHILVOCS)- government agency concerned with earthquakes and volcanic eruptions in the Philippines
• Circumpacific Ring of Fire or Pacific Ring of Fire- it is a 2500-mile chain of volcanoes and seismically active sites of Earthquakes and volcanic eruptions. It is also an area where crustal plates are weak
• Volcano- opening in the Earth’s crust where lava, molten rocks, and gaseous materials are forced out through the opening
• Vent- an opening, as in a wall, serving as an outlet for air, smoke, and fumes
• Crater- the cone-shaped mountain with a funnel-shaped opening
• Lava Flow- a stream or sheet of molten or solidified lava
• Sill- an intrusive body of magma that pushes its way between layers of sediment
• Ash Cloud- a cloud of gas, steam, ash, dust, and coarser fragments that form during an explosive volcanic eruption and commonly gets blown long distances
• Secondary Vent- a vent or tube that connects to the secondary cone for the lava to flow
• Throat- entrance of a volcano. The part of a conduit that ejects lava and volcanic ash
• Conduit- an underground passage where magma travels through
• Magma Chamber- a reservoir of magma in the Earth’s crust where the magma may reside temporarily on its way from the upper mantle to the Earth’s surface
• Explosive Volcanic Eruption- large amounts of pyroclastic materials are ejected by the volcano into the air. It occurs when gasses in magma are trapped, causing a build-up of pressure in the magma chamber
• Pyroclastic Materials- contains lava, ashes, volcanic gases, and rocks
• Non-Explosive Eruption- lava just flows out of the crater and the gaps of the volcano. This kind of eruption happens when there is less pressure in the magma chamber
• Kinds of Stages of Volcano

  ·        Active Volcano- currently erupting or showing regular signs of activity like earthquakes, and significant gas emission
• ·        Dormant Volcano- erupted and then entered a long period of inactivity. It is also called as “Sleeping Volcano”